In general, printed circuit boards (PCBs) are components that become the basis for various electrical and electronic products.
In other words, PCBs are essential for household electrical appliances. In recent years, miniaturized, high-density, and high-performance printed circuit boards have been used for semiconductor modules, semiconductor inspection devices, automobiles, as well as defense industry advanced weapon such as missile warheads, fighters and satellites. The use of PCBs is gradually expanding.
A conventional printed circuit board is classified into a rigid printed circuit board in which a copper foil is adhered to a core material to which a reinforcing material such as glass fibers is added to an epoxy resin, a flexible printed circuit board (FPCB) in which a copper foil is adhered to a Polyimide substrate, and a rigid-flexible printed circuit board (RF PCB) that combines the merits of a rigid printed circuit board with a flexible printed circuit board. The respective PCBs are used in accordance with their characteristics.
Meanwhile, future type devices to be developed and utilized in the future are expected to be structurally and conceptually different from existing devices. In particular, recently, glasses, clothing, and the like, which are worn on the human body for convenient human life, are beginning to be developed by being built in together with electronic components.
Development of a wearable printed circuit board in the course of such changes may facilitate the development of future type devices such as smart clothes, and research and development of the technology will be necessary.
Korean Patent Registration No. 10-1139970 (Patent Document 1) discloses a method of manufacturing a flexible printed circuit board, the method comprising: a first step of forming a circuit pattern on a seed layer formed on a flexible insulating substrate; a second step of applying a first photosensitive material on the circuit pattern; a third step of exposing and developing the first photosensitive material to form a protective pattern on the circuit pattern; a fourth step of etching the seed layer; and a fifth step of peeling off the protective pattern, wherein the first photosensitive material is a liquid or film type photosensitive material.
Patent Document 1 discloses implementing a flexible printed circuit board. However, since the base member is a flexible insulating substrate such as a polyimide film, there is no restoring characteristic of being folded, crumpled and then spread again, and there is no air-permeability. As a result, such a flexible printed circuit board is not applicable to smart clothes and the like which require wearability.